| Niklas Backstrom (inactive) | | 1-2-0 | Sweden | Jun 20, 2015 |
| Seth Baczynski (inactive) | The Polish Pistola | 5-6-0 | United States | Apr 11, 2015 |
| Ryan Bader (inactive) | Darth | 15-5-0 | United States | Nov 19, 2016 |
| Izabela Badurek (inactive) | | 0-1-0 | United States | Apr 11, 2015 |
| Miguel Baeza (inactive) | Caramel Thunder | 3-4-0 | United States | Jun 8, 2024 |
| Ali Bagautinov (inactive) | Puncher | 4-3-0 | Russia | Nov 19, 2016 |
| Mehdi Baghdad (inactive) | The Sultan | 0-2-0 | France | Jul 7, 2016 |
| Melsik Baghdasaryan | The Gun | 3-3-0 | Armenia | Jun 20, 2026 |
| Siyar Bahadurzada (inactive) | The Great | 4-4-0 | Afghanistan | Sep 28, 2019 |
| Ignacio Bahamondes | La Jaula | 7-4-0 | Chile | Sep 12, 2026 |
| Shamar Bailey (inactive) | | 1-2-0 | United States | Nov 19, 2011 |
| Scott Baker (inactive) | | 0-1-0 | United States | Mar 11, 1994 |
| Oluwale Bamgbose (inactive) | Holy War Angel | 1-4-0 | United States | Dec 16, 2017 |
| Marcin Bandel (inactive) | Bomba | 0-2-0 | Poland | Apr 11, 2015 |
| Humberto Bandenay (inactive) | | 1-3-0 | Peru | Aug 10, 2019 |
| Tae Hyun Bang (inactive) | Supernatural | 2-3-0 | South Korea | Sep 3, 2016 |
| Shauna Bannon | Mama B | 2-3-0 | Ireland | May 16, 2026 |
| Antonio Banuelos (inactive) | | 0-1-0 | United States | Feb 5, 2011 |
| Iwo Baraniewski | Rudy | 3-1-0 | Poland | Sep 19, 2026 |
| Renan Barao (inactive) | The Baron | 9-8-0 | Brazil | Nov 16, 2019 |
| Maycee Barber | The Future | 10-3-0 | United States | Mar 28, 2026 |
| Bryan Barberena | Bam Bam | 9-10-0 | United States | Mar 16, 2024 |
| Dione Barbosa | The Witch | 4-2-0 | Brazil | Jul 18, 2026 |
| Marcio Barbosa | Ticoto | 2-0-0 | Brazil | Aug 22, 2026 |
| Edson Barboza (inactive) | Junior | 18-15-0 | Brazil | Aug 15, 2026 |
| Raoni Barcelos | | 11-5-0 | Brazil | Sep 26, 2026 |
| Daniel Barez (inactive) | | 1-3-0 | Spain | May 16, 2026 |
| Danny Barlow (inactive) | LeftHand2God | 2-2-0 | United States | Oct 18, 2025 |
| Luke Barnatt (inactive) | The Bigslow | 3-3-0 | United States | May 16, 2015 |
| Chris Barnett (inactive) | Beastboy | 2-4-0 | Spain | Oct 25, 2025 |
| Josh Barnett (inactive) | The Warmaster | 7-3-0 | United States | Sep 3, 2016 |
| David Baron (inactive) | | 0-1-0 | France | Oct 18, 2008 |
| Phil Baroni (inactive) | The New York Bad Ass | 3-7-0 | United States | Jan 1, 2011 |
| Dan Barrera (inactive) | The Fireman | 0-1-0 | United States | Dec 8, 2007 |
| Carlos Barreto (inactive) | | 0-1-0 | Unknown | Oct 17, 1997 |
| Peter Barrett (inactive) | Slippery | 0-2-0 | United States | Dec 12, 2020 |
| Marc-Andre Barriault | Powerbar | 6-10-0 (1 NC) | Canada | Feb 7, 2026 |
| Alexandre Barros (inactive) | Baixinho | 0-1-0 | United States | Jan 17, 2009 |
| Francimar Barroso (inactive) | Bodao | 4-4-0 (1 NC) | United States | Jan 20, 2018 |
| Dean Barry (inactive) | The Sniper | 0-1-0 | Unknown | Apr 23, 2022 |
| Pat Barry (inactive) | HD | 5-7-0 | United States | Dec 6, 2013 |
| Enrique Barzola (inactive) | El Fuerte | 6-3-1 | Peru | Mar 14, 2020 |
| Farid Basharat | Ferocious | 7-0-0 | Afghanistan | Jul 11, 2026 |
| Javid Basharat (inactive) | The Snow Leopard | 4-2-0 (1 NC) | Afghanistan | Feb 7, 2026 |
| Austin Bashi | | 1-2-0 | United States | Jul 18, 2026 |
| Stephen Bass (inactive) | Bigfish | 0-1-0 | United States | Dec 3, 2011 |
| Shayna Baszler (inactive) | The Queen of Spades | 0-2-0 | United States | Mar 21, 2015 |
| Namsrai Batbayar | Steppe Warrior | 0-1-0 | Mongolia | Aug 29, 2026 |
| Michel Batista (inactive) | | 0-1-0 | Cuba | Nov 30, 2018 |
| Bryan Battle (inactive) | The Butcher | 7-1-0 (1 NC) | United States | Dec 7, 2024 |
| Alan Baudot (inactive) | The Black Samourai | 0-3-0 (1 NC) | France | Jun 25, 2022 |
| Mario Bautista | | 12-3-0 | United States | Jul 11, 2026 |
| Chris Beal (inactive) | Real Deal | 2-3-0 | United States | Jun 18, 2016 |
| Ariel Beck (inactive) | | 0-1-0 | United States | Dec 1, 2017 |
| Johnny Bedford (inactive) | Brutal | 2-3-0 (1 NC) | United States | Sep 13, 2014 |
| Rolando Bedoya (inactive) | The Machine | 0-4-0 | Peru | Sep 27, 2025 |
| Azamat Bekoev | Iron | 2-2-0 | Russia | Apr 4, 2026 |
| Mirsad Bektic (inactive) | | 6-4-0 | Bosnia & Herzegovina | Sep 19, 2020 |
| Diana Belbita (inactive) | The Warrior Princess | 2-6-0 | Romania | Apr 5, 2025 |
| Alan Belcher (inactive) | The Talent | 9-6-0 | United States | Apr 27, 2013 |
| Vitor Belfort (inactive) | The Phenom | 15-10-0 (1 NC) | Brazil | May 12, 2018 |
| Yousri Belgaroui | | 3-0-0 | Netherlands | Sep 12, 2026 |
| Rodolfo Bellato | Trator | 2-2-1 (1 NC) | Brazil | Sep 26, 2026 |
| Danilo Belluardo (inactive) | Caterpillar | 0-2-0 | Italy | Sep 28, 2019 |
| Joey Beltran (inactive) | The Mexicutioner | 3-6-0 (1 NC) | United States | Oct 9, 2013 |
| Marco Beltran (inactive) | Psycho | 3-3-0 | Mexico | Oct 7, 2017 |
| Joseph Benavidez (inactive) | | 15-6-0 | United States | Mar 6, 2021 |
| Dave Beneteau (inactive) | Dangerous | 3-3-0 | Canada | Oct 17, 1997 |
| Gabriel Benitez (inactive) | Moggly | 7-8-0 | Mexico | Apr 27, 2024 |
| DeAnna Bennett (inactive) | The Argentine Assassin | 0-0-1 | United States | Dec 1, 2017 |
| Lance Benoist (inactive) | | 2-2-0 | United States | Jun 7, 2014 |
| Ryan Benoit (inactive) | Baby Face | 3-6-0 | United States | Jul 31, 2021 |
| Delphine Benouaich | | 1-0-0 | France | Sep 5, 2026 |
| Steve Berger (inactive) | The Red Nosed Pitbull | 0-2-0 (1 NC) | United States | Jun 22, 2002 |
| Theodor Berggren | Simba | 0-1-0 | Sweden | Jun 27, 2026 |
| Keith Berish (inactive) | Sha Bang Bang | 0-1-0 (1 NC) | United States | Dec 9, 2016 |
| Dennis Bermudez (inactive) | The Menace | 10-7-0 | Unknown | Jan 19, 2019 |
| Manny Bermudez (inactive) | The Bermudez Triangle | 3-2-0 | United States | Oct 18, 2019 |
| Talita Bernardo (inactive) | | 1-3-0 | Brazil | May 11, 2019 |
| Dave Berry (inactive) | | 0-1-0 | Unknown | Sep 20, 1996 |
| Dieusel Berto (inactive) | | 0-1-0 | Unknown | Jul 12, 1996 |
| Allen Berube (inactive) | Monstah Lobstah | 0-1-0 | United States | Jun 23, 2007 |
| Scott Bessac (inactive) | | 1-1-0 | Unknown | Dec 16, 1995 |
| Matt Bessette (inactive) | The Mangler | 0-2-0 | United States | Jul 6, 2018 |
| Arjan Bhullar (inactive) | | 3-1-0 | Canada | May 4, 2019 |
| KB Bhullar (inactive) | The Bengal | 0-2-0 | Canada | May 1, 2021 |
| Magomed Bibulatov (inactive) | Chaborz | 1-2-0 | Russia | Feb 2, 2019 |
| David Bielkheden (inactive) | | 1-2-0 | Sweden | Apr 18, 2009 |
| Blake Bilder (inactive) | El Animal | 1-2-0 | United States | Feb 3, 2024 |
| Anthony Birchak (inactive) | El Toro | 2-4-0 | United States | Apr 17, 2021 |
| Michael Bisping (inactive) | The Count | 20-9-0 | United Kingdom | Nov 25, 2017 |
| Amaury Bitetti (inactive) | | 1-1-0 | Brazil | Jun 9, 2000 |
| Jan Blachowicz | | 12-9-2 | Poland | Aug 1, 2026 |
| Jason Black (inactive) | The Black Legion | 0-2-0 | United States | Oct 20, 2007 |
| Tina Black | | 1-0-0 | Unknown | Sep 26, 2026 |
| Brad Blackburn (inactive) | Bad Brad | 3-2-0 | United States | Apr 10, 2010 |
| Tom Blackledge (inactive) | | 0-1-0 | United Kingdom | Feb 26, 2011 |
| Da'Mon Blackshear | The Monster | 5-4-1 | United States | Jul 26, 2025 |
| Erin Blanchfield | Cold Blooded | 8-1-0 | United States | Nov 15, 2025 |
| Maximo Blanco (inactive) | Maxi | 4-5-0 | Venezuela | Sep 17, 2016 |
| Curtis Blaydes | Razor | 15-6-0 (1 NC) | United States | Sep 12, 2026 |
| Tereza Bleda | | 1-2-0 | Czechia | Dec 13, 2025 |
| Byron Bloodworth (inactive) | | 0-2-0 | United States | Dec 29, 2012 |
| Dan Bobish (inactive) | | 1-1-0 | United States | Jul 27, 1997 |
| Mark Bocek (inactive) | | 8-5-0 | Canada | Apr 16, 2014 |
| Kyle Bochniak (inactive) | Killer B | 2-5-0 | United States | Oct 18, 2019 |
| James Bochnovic (inactive) | | 0-2-0 | United States | May 12, 2018 |
| Tim Boetsch (inactive) | The Barbarian | 12-12-0 | United States | Mar 9, 2019 |
| Galore Bofando (inactive) | | 1-1-0 | Unknown | Dec 16, 2017 |
| Roman Bogatov (inactive) | | 0-1-0 | Kazakhstan | Jul 11, 2020 |
| Jerry Bohlander (inactive) | | 5-2-0 | United States | Jan 8, 1999 |
| Mandy Bohm | Monster | 1-2-0 | Germany | May 13, 2023 |
| Gaston Bolanos | The Dreamkiller | 3-2-0 | Peru | Jun 20, 2026 |
| Denys Bondar | Psycho | 0-3-0 | Ukraine | Feb 24, 2024 |
| Gabriel Bonfim | Marretinha | 7-1-0 | Brazil | Jun 6, 2026 |
| Ismael Bonfim | Marreta | 2-4-0 | Brazil | Jul 25, 2026 |
| Jesse Bongfeldt (inactive) | Water | 0-1-1 | Canada | Jun 11, 2011 |
| Stephan Bonnar (inactive) | The American Psycho | 8-7-0 | United States | Oct 13, 2012 |
| Rogerio Bontorin (inactive) | | 2-3-0 (1 NC) | Brazil | Jan 15, 2022 |
| Mara Romero Borella (inactive) | | 2-5-0 | Italy | Sep 19, 2020 |
| Ray Borg (inactive) | The Tazmexican Devil | 7-5-0 | United States | May 13, 2020 |
| Kevin Borjas | El Gallo Negro | 2-5-0 | Peru | Aug 29, 2026 |
| Caio Borralho | The Natural | 8-1-0 | Brazil | Mar 7, 2026 |
| Viacheslav Borshchev (inactive) | Slava Claus | 3-6-1 | Russia | Nov 15, 2025 |
| Tanner Boser | The Bulldozer | 5-6-0 | Canada | Apr 18, 2026 |
| Steve Bosse (inactive) | The Boss | 2-1-0 | Canada | Jun 18, 2016 |
| Marcus Bossett (inactive) | The Grasshopper | 1-2-0 | Unknown | Dec 7, 1996 |
| Poliana Botelho (inactive) | | 3-4-0 | Brazil | Jun 4, 2022 |
| Tai Bowden (inactive) | | 1-1-0 | Unknown | Dec 7, 1996 |
| Melton Bowen (inactive) | The Punisher | 0-1-0 | United States | Dec 16, 1994 |
| Brian Bowles (inactive) | | 2-2-0 | United States | May 25, 2013 |
| Roger Bowling (inactive) | Relentless | 0-2-0 (1 NC) | United States | Dec 14, 2013 |
| Kyle Bradley (inactive) | | 1-3-0 | Unknown | Jan 11, 2010 |
| Paul Bradley (inactive) | The Gentleman | 0-2-0 | Unknown | Nov 12, 2011 |
| Sean Brady | | 9-2-0 | United States | May 9, 2026 |
| Ebenezer Fontes Braga (inactive) | Pitbull | 1-0-0 | Unknown | Oct 16, 1998 |
| Ramiz Brahimaj | | 5-5-0 | United States | Aug 15, 2026 |
| Joe Brammer (inactive) | The South Side Strangler | 0-2-0 | United States | May 29, 2010 |
| David Branch (inactive) | | 4-5-0 | United States | Mar 30, 2019 |
| Diego Brandao (inactive) | DB | 6-4-0 | Brazil | Jan 2, 2016 |
| Bruna Brasil (inactive) | | 2-5-0 | Brazil | Mar 28, 2026 |
| Martin Bravo (inactive) | El Toro | 1-3-0 | Mexico | Sep 21, 2019 |
| Mike Breeden (inactive) | Money | 1-3-0 | United States | Oct 21, 2023 |
| Tom Breese (inactive) | | 5-3-0 | United Kingdom | Jan 20, 2021 |
| Elves Brener | | 4-3-0 | Brazil | Sep 26, 2026 |
| Chris Brennan (inactive) | The Westside Strangler | 1-2-0 | Unknown | Jan 11, 2002 |
| Lucas Brennan | Skywalker | 0-1-0 | United States | Apr 25, 2026 |
| Charlie Brenneman (inactive) | The Spaniard | 4-7-0 | United States | Nov 8, 2014 |
| Jason Brilz (inactive) | Hitman | 3-4-0 | United States | Nov 19, 2011 |
| Marcus Brimage (inactive) | The Bama Beast | 4-4-0 | United States | Jul 18, 2015 |
| Aaron Brink (inactive) | | 0-1-0 | United States | Nov 17, 2000 |
| Henry Briones (inactive) | Bure | 1-4-0 | Mexico | May 19, 2018 |
| Joanderson Brito | Tubarao | 8-3-0 | Brazil | Sep 19, 2026 |
| Jonathan Brookins (inactive) | | 2-3-0 | United States | Dec 15, 2012 |
| Jarred Brooks (inactive) | The Monkey God | 2-2-0 | United States | Sep 8, 2018 |
| Will Brooks (inactive) | Ill | 1-3-0 | United States | Nov 18, 2017 |
| Rob Broughton (inactive) | The Bear | 1-2-0 | United Kingdom | Nov 5, 2011 |
| Damien Brown (inactive) | Beatdown | 2-4-0 | Unknown | Feb 10, 2018 |
| Matt Brown (inactive) | The Immortal | 17-13-0 | United States | May 13, 2023 |
| Mike Brown (inactive) | | 2-4-0 | United States | Aug 17, 2013 |
| Randy Brown | Rudeboy | 14-8-0 | Jamaica | Apr 11, 2026 |
| TJ Brown (inactive) | Downtown | 3-5-0 | United States | Oct 14, 2023 |
| Todd Brown (inactive) | Bulldog | 0-2-0 | United States | Mar 3, 2011 |
| Travis Browne | Hapa | 9-7-1 | United States | Jul 8, 2017 |
| Junie Browning (inactive) | | 1-1-0 | United States | Apr 1, 2009 |
| Jules Bruchez (inactive) | | 0-1-0 | United States | Dec 13, 2008 |
| Cody Brundage | | 6-8-1 (1 NC) | United States | May 16, 2026 |
| Fernando Bruno (inactive) | Acougueiro | 0-2-0 | Unknown | Jul 8, 2016 |
| Steve Bruno (inactive) | Hollywood | 1-2-0 | United States | Feb 7, 2009 |
| Derek Brunson (inactive) | The One | 14-7-0 | United States | Mar 4, 2023 |
| Josh Bryant (inactive) | The Beast | 0-1-0 | United States | Jun 19, 2010 |
| Robert Bryczek | | 1-3-0 | Poland | Sep 26, 2026 |
| Lukasz Brzeski (inactive) | The Bull | 1-6-0 | Poland | Jul 19, 2025 |
| Marcus Buchecha | | 0-2-1 | Brazil | Apr 25, 2026 |
| Justin Buchholz (inactive) | | 1-4-0 | United States | Feb 6, 2010 |
| Joaquin Buckley | New Mansa | 11-6-0 | United States | May 9, 2026 |
| Martin Buday (inactive) | Badys | 7-1-0 | Slovakia | Jul 26, 2025 |
| Dylan Budka (inactive) | The Mindless Hulk | 0-3-0 | United States | Feb 15, 2025 |
| Paul Buentello (inactive) | The Headhunter | 3-3-0 | United States | Mar 21, 2010 |
| Marek Bujlo (inactive) | Bujdzilla | 0-1-0 | Poland | Nov 22, 2025 |
| Modestas Bukauskas | The Baltic Gladiator | 9-5-0 | Lithuania | Sep 5, 2026 |
| Felipe Bunes (inactive) | Felipinho | 1-3-0 | Brazil | Feb 28, 2026 |
| Matt Van Buren (inactive) | Gutter | 0-2-0 | United States | Jan 18, 2015 |
| Shane Burgos (inactive) | Hurricane | 8-3-0 | United States | Jul 16, 2022 |
| Joshua Burkman (inactive) | The People's Warrior | 6-12-0 (1 NC) | United States | Feb 18, 2018 |
| Mads Burnell (inactive) | | 1-2-0 | Denmark | May 27, 2018 |
| Mikey Burnett (inactive) | The Eastside Assassin | 2-1-0 | United States | Jan 8, 1999 |
| Gilbert Burns (inactive) | Durinho | 15-10-0 | Brazil | Apr 18, 2026 |
| Herbert Burns (inactive) | The Blaze | 2-4-0 | Brazil | Aug 17, 2024 |
| Kevin Burns (inactive) | The Fire | 2-3-0 | United States | Dec 12, 2009 |
| Nah-Shon Burrell (inactive) | The Rock n Rolla | 1-1-0 | United States | May 25, 2013 |
| Bubba Bush (inactive) | The Fightin' Texas Aggie | 0-1-0 (1 NC) | United States | Oct 24, 2015 |
| Dakota Bush (inactive) | | 0-2-0 | United States | Jan 15, 2022 |
| Murilo Bustamante (inactive) | | 3-1-0 | Brazil | May 10, 2002 |
| Jesse Butler (inactive) | | 0-2-0 | United States | Jun 8, 2024 |
| Todd Butler (inactive) | | 0-1-0 | Unknown | Jul 27, 1997 |
| JP Buys | Young Savage | 0-4-0 | South Africa | Aug 12, 2023 |
| Dennis Buzukja | The Great | 1-5-0 | United States | Aug 1, 2026 |
| Charles Byrd (inactive) | Kid Dynamite | 1-3-0 | United States | Jun 6, 2020 |
| Steve Byrnes (inactive) | The Sergeant | 0-1-0 | Unknown | Dec 13, 2006 |